1. Field of the Invention
The present invention relates to a device for removing an improper weft when a weft is not properly inserted into the open shed of warps in an air jet loom.
2. Description of Related Art
An improper weft removing device extracts an improper weft existing in the open shed of the warps out of the open shed and removes the same. Further, the improper weft removing device preferably has a function of judging whether the whole of the improper weft has been removed or only a part of the improper weft has been removed with the remainder (cut piece) of the improper weft left in the open shed of the warps. This is because, if the improper weft removing device judges that the whole of the improper weft has been removed, the loom can be automatically returned to the regular operation after the removal of the improper weft, and on the other hand, if the device judges that the cut piece of the improper weft is left in the open shed of the warps, the cut piece is required to be removed by any other means.
An improper weft removing device is known in which an improper weft suction box member containing a pair of feed rollers thereinside is provided. According to this, an air suction force (or an air blowing force) acts on the improper weft so as to deviate the improper weft from the regular weft inserting path and bend the same in a U-shaped form. Then the improper weft is cut at a location in the vicinity of the main nozzle by a weft cutter, and the cut improper weft is introduced into the improper weft suction box member. The improper weft introduced into the suction box member is held by the pair of feed rollers and then delivered toward a discharge dust box.
In this improper weft removing device, the rotation member of the feed roller is calculated and the length of the improper weft is calculated based on the obtained rotation number and the outer diameter of the feed roller.
However, in this prior art, since when the improper weft is extracted out of the warps at the time of discharging the improper weft, the friction resistance varies at the beginning and at the end of the improper weft discharge, since the end portion of the improper weft separated from the outer end of the warps is left free, and since the air suction force (or air blowing force) is acting on the improper weft, often the end portion of the improper weft is wound at one time on the feed rollers or the end portion of the improper weft is delivered disadvantageously in the entangled state to the feed rollers. If the improper weft in such a state is delivered toward the discharge dust box, the length of the improper weft cannot be precisely calculated and the device erroneously judges that the cut piece of the improper weft is still left in the open shed of the warps even after extracting the whole of the improper weft therefrom.